Abstract: Information on stability and continuity of welding process can be obtained by dynamic monitoring of weld pool.The dynamic monitoring of weld pool is still in laboratory stage.To monitor weld pool in the welding scene is more valuable in both welding process improvement and production guide.However, there are some problems in welding scene, for example, the welding power sources cannot be modified and incontrollable by personal computer; the waveforms of welding current and voltage are unknown and so on.For these problems, a weld pool image dynamic monitoring system was setup in the welding scene.According to the characteristics of pulsed GTAW (gas tungsten arc welding) in the welding scene, the time to take image, which is the most important factor to restrict to take image in the welding scene, is determined by external synchronization; using the spectral analysis, a compound filter system, which reduces the interference of arc, was proposed;at the optimum image taking hour, clear images of weld pool were obtained by CCD with the compound filter system in the welding scene.